This patent specification relates to the general field of osteoporosis diagnosis, bone density, and vertebral imaging, and in particular to using a single device to predict future fracture risk by combining several measurements made on a single device along with biographical and/or other information about a patient to produce an estimate of the patient""s future risk of bone fracture.
Dual-energy bone densitometers such as the QDR machines manufactured by the assignee hereof, Hologic Corporation of Bedford, MA, and similar devices manufactured by LUNAR Corporation and Norland Corporation are used to measure Bone Mineral Density (BMD) and Bone Mineral Content (BMC) of the spine, hip, and peripheral sites. See, e.g., U.S. Pat. Nos. 5,771,272, 5,778,045, 5,835,555, and 5,838,765, which are hereby incorporated by reference. These devices use the information from a particular BMD measurement at a particular site to classify patients with respect to their risk for future fractures. Further, some of the bone densitometer machines, namely the QDR4500A by Hologic and the Expert by LUNAR are capable of imaging the spine in the supine lateral position. The image of the spine thus obtained is used for quantitative morphometric analysis by the placing of points on the image and measuring morphometric parameters as discussed, for example, in U.S. Pat. Nos. 5,850,836, 5,673,298, and 5,483,960, which are hereby incorporated by reference. These quantitative morphometric measurements may be combined with values related to the bone mass to indicate the likelihood of future vertebral fractures in the vertebra. However, in spite of attempts at automating the calculation of morphometric indicia and the placement of points on the digital image provided by the bone densitometers, the procedure of quantitative morphometry to determine vertebral deformity (or fracture) can be labor intensive and tedious. Further, some of the bone densitometry machines use both a single energy and dual energy scan of the lumbar-thoracic spine. The single energy scan is faster and has a lower dose, but in the thoracic part of the spine soft tissue can sometimes obscure the vertebral endplates. The dual-energy scan subtracts out the soft tissue artifacts seen in the thoracic region and displays only the bone image. But dual-energy imaging, because it is effectively a difference of two images, has difficulty obtaining a high enough signal-to-noise ratio in the lumbar region of thicker patients using the low dose x-ray sources typically employed in densitometry. Besides morphometric imaging in the supine lateral position (patient lying on her or his back), some bone densitometers (e.g. QDR4500C by Hologic) have an imaging mode that allows imaging of the vertebral column while the patient is in a decubitus position, lying on her or his side. This positioning of the patient allows the physician to look for fractures in much the same way as when a supine lateral view is taken. There are services available on the Internet or through software licenses that combine information obtained from BMD measurements, information about significant prevalent fractures, ethnicity and age of a patient to calculate Remaining Lifetime Fracture Probability (RLFP). In the service located at www.medsurf.com, the physician types in information about the patient and the software generates a report, which includes an estimate of the likelihood of future fractures. In particular, this software emphasizes the probability that a patient, typically a woman, will have a fracture during her remaining lifetime. Many other methods of reporting fracture have been discussed in the literature and include the probability of a fracture within a specified time frame (e.g., 1 year), the relative risk of fracture compared to other patients of the same sex, ethnicity, and age, or simply qualitative measures such as not increased, increased, and high risk compared to a reference population (which may or may not have the same sex, age, and/or ethnicity). Factual bases for determining a patient""s future risk of fracture are discussed in many studies of a relationship between future fracture risk and such factors as age, sex, ethnicity, BMD, prevalent vertebral fracture, maternal history of fracture, corticoid use, etc. Other information can also be used for fracture risk estimates, including information from ultrasound bone units such as the Sahara unit manufactured by Hologic and from biochemical test strips. See, e.g., U.S. Pat. No. 5,785,041, incorporated herein by reference. Fracture risk can also be divided by fracture site, with hip fractures often being a separate category because of the significant cost and morbidity associated with this type of osteoporotic fracture.
The following documents may be of interest to the device and method disclosed herein, and are hereby incorporated by reference: (1) J. A. Rea et. al.xe2x80x94Bone Vol. 23, Number 5, Supplement pg. S160; (2) S. R. Cummings et. al. The New England Journal of Medicine, Mar. 23, 1995 Vol. 332 No. 12 xe2x80x9cRisk Factors for Hip Fracture in White Women;xe2x80x9d (3) C. C. Gluer et. al.xe2x80x94Radiology 1996; 199:725-732 xe2x80x9cOsteoporosis: Association of Recent Fractures with Quantitative US Findings;xe2x80x9d (4) D. C. Bauer et. al., Archives of Internal Medicine Mar. 2, 1997, Vol. 157 Pg. 629 xe2x80x9cBroadband Ultrasound Attenuation Predicts Fractures Strongly and independently of densitometry in Older Women;xe2x80x9d (5) H. Genant et al.xe2x80x94Journal of Bone and Mineral Research Vol. 8, Number 9, 1993, pg. 1137 and J. Bone and Mineral Research Vol. 11 Number 7, 1996; (6) J. A. Kanisxe2x80x94Osteoporsis Int. (1997) 7:390-406 xe2x80x9cGuidelines for diagnosis and management of Osteoporosis;xe2x80x9d (7) J. A. Kanis Osteoporosis International (1997) 7 (Suppl. 3):S108-S116 xe2x80x9cDiagnosis of Osteoporosis;xe2x80x9d (8) National Osteoporosis Foundation Guidelines 1998 (see, e.g., FIG. 4); (9) Merrill""s Atlas of Radiographic Positions and Radiologic Procedures 9th ed. Vol.1 pg. 420-421; (10) M. C. Nevitt et. al. Bone Vol. 25 No. 5, November 1999:613-619; (11) P. D. Ross et. al. Osteoporosis Int. (1993) 3:120-126 xe2x80x9cPredicting Vertebral Fracture Incidence from Prevalent Fractures and Bone Density among Non-Black, Osteoporotic Women;xe2x80x9d (12) S. J. Jacobsen et. al. Epidemiology 1992 3(6):515-8 xe2x80x9cHospitalization with vertebral fracture among the aged: a national population-based study;xe2x80x9d (13) M. A. Kotowicz et. al., Journal of Bone Mineral Research xe2x80x9cRisk of hip fracture in women with vertebral fracture;xe2x80x9d (14) P. D. Ross et. al. Osteoporosis International 1993; 3(3): 120-126 xe2x80x9cPredicting vertebral fracture incidence from prevalent fractures and bone density among non-black, osteoporotic women;xe2x80x9d (15) L. J. Melton 3rd, et. al. Osteoporosis International 1999 10(3):214-221 xe2x80x9cVertebral Fractures Predict Subsequent Fractures;xe2x80x9d (16) The Merck Manual of Geriatricsxe2x80x94Section 82 xe2x80x9cDisorders of Mineral Metabolismxe2x80x9d www.merck.com/pubs/mm_geriatrics/toc.htm; (17) FDA 510kxe2x80x94FDA pre-market notification k9972775 clearance date Oct. 1, 1999. MXA-II software option; (18) QDR 4500 Image Worksxe2x80x94View User Guide Hologic Doc. No. 080-0570 Rev. C Copyright 1996.
This patent specification discloses a device and a method in which an integrated device that not only measures bone mineral density (BMD) and provides an image that is useful for determining prevalent vertebral fractures, but also combines the BMD and the prevalent vertebral fracture information with biographical information and/or other risk factors to provide an indicator of a patient""s future fracture risk to the physician (or other health services provider). This saves the physician time, prevents transcription errors, and provides a single report that the physician can provide to and discuss with the patient or the patient""s referring physician. It also can help increase the accuracy of the diagnosis, since usually risk factors are not completely independent of each other, and could be combined based on relationships found in clinical studies. To combine such risk factors otherwise can be tedious and time consuming, and can require an extensive literature search. Moreover, by summarizing this information along with the scan reports and making this quickly available, the device and method disclosed herein can allow the physician to immediately discuss these results with the patient and can eliminate the need for the patient to have a return visit. Further, this arrangement can provide a single-energy X-ray scan of the entire lumbar-thoracic region, with the operator selecting a part of this region for repeat scanning using a dual-energy X-ray scan mode. This is useful because the single-energy scan is of a much lower dose and is much quicker, and only sometimes will it be necessary to repeat a certain part of the scan with a dual-energy scan. Thus, dose to the patient and time are conserved, especially since scan time for the dual-energy scan is approximately linearly proportional to the length of spine under examination. A typical single-energy high resolution scan requires 12 seconds for 18 inches, compared with 6 minutes for 18 inches for dual-energy on a QDR4500A. Also allowed, is for a scan window to be set on a dual-energy image, and another scan with different technique factors (collimators, dose, dual- or single-energy) performed based on the window set. The arrangement disclosed herein also allows different images to be displayed side by side and compared, for example, a single and dual energy lateral image, or two images taken on different dates.